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<a name="MIPS-ISA"></a>
<div class="header">
<p>
Next: <a href="MIPS-assembly-options.html#MIPS-assembly-options" accesskey="n" rel="next">MIPS assembly options</a>, Previous: <a href="MIPS-Small-Data.html#MIPS-Small-Data" accesskey="p" rel="prev">MIPS Small Data</a>, Up: <a href="MIPS_002dDependent.html#MIPS_002dDependent" accesskey="u" rel="up">MIPS-Dependent</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="AS-Index.html#AS-Index" title="Index" rel="index">Index</a>]</p>
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<hr>
<a name="Directives-to-override-the-ISA-level"></a>
<h4 class="subsection">9.27.5 Directives to override the ISA level</h4>

<a name="index-MIPS-ISA-override"></a>
<a name="index-_002eset-mipsn"></a>
<p><small>GNU</small> <code>as</code> supports an additional directive to change
the MIPS Instruction Set Architecture level on the fly: <code>.set
mips<var>n</var></code>.  <var>n</var> should be a number from 0 to 5, or 32, 32r2, 32r3,
32r5, 32r6, 64, 64r2, 64r3, 64r5 or 64r6.
The values other than 0 make the assembler accept instructions
for the corresponding ISA level, from that point on in the
assembly.  <code>.set mips<var>n</var></code> affects not only which instructions
are permitted, but also how certain macros are expanded.  <code>.set
mips0</code> restores the ISA level to its original level: either the
level you selected with command-line options, or the default for your
configuration.  You can use this feature to permit specific MIPS III
instructions while assembling in 32 bit mode.  Use this directive with
care!
</p>
<a name="index-MIPS-CPU-override"></a>
<a name="index-_002eset-arch_003dcpu"></a>
<p>The <code>.set arch=<var>cpu</var></code> directive provides even finer control.
It changes the effective CPU target and allows the assembler to use
instructions specific to a particular CPU.  All CPUs supported by the
&lsquo;<samp>-march</samp>&rsquo; command-line option are also selectable by this directive.
The original value is restored by <code>.set arch=default</code>.
</p>
<p>The directive <code>.set mips16</code> puts the assembler into MIPS 16 mode,
in which it will assemble instructions for the MIPS 16 processor.  Use
<code>.set nomips16</code> to return to normal 32 bit mode.
</p>
<p>Traditional MIPS assemblers do not support this directive.
</p>
<p>The directive <code>.set micromips</code> puts the assembler into microMIPS mode,
in which it will assemble instructions for the microMIPS processor.  Use
<code>.set nomicromips</code> to return to normal 32 bit mode.
</p>
<p>Traditional MIPS assemblers do not support this directive.
</p>
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